One definition of an advanced civilization is "having a specialized division of labor". Many companies need specialized professionals' services less than full-time, or their needs fluctuate a lot over time. If they are hired full-time, they may need to "wear many hats", doing a lot of work they probably find boring. On the other hand, being around full-time helps them be part of the company's culture and community, and understand the unspoken factors that may make an outsider's services less effective. However exposure to multiple companies is also very helpful, to expand their horizons about the possible range of approaches. Also, being more specialized encourages them to understand their profession more deeply and keep up with new methods. In the past, increases in specialization have usually been accompanied by higher productivity. The complexity of business and society today imply that there may be even more scope for such improvements.
If I can do a job -- from giving legal advice to fixing plumbing to debugging a program or consulting on a specialized electronic design problem -- in one company, and simply walk to the door on the same floor (SkyTranEqualsElevator), speak a destination and be at another company miles away in ten minutes, I can afford to be much more specialized. Companies can afford to bring in a highly-skilled expert for a half hour instead of having an employee struggle all morning to solve a problem outside her expertise.
Not only high-level but low-level jobs could become very specialized with near-instant travel. This could be a problem. If Jose's job is cleaning toilets in the bathrooms of 100 businesses a day -- all toilets, all the time -- his job satisfaction may not be the highest. On the other hand, this could be an opportunity. Someone who is severely retarded is likely to be much happier (not to mention productive and well-socialized) traveling all over town doing a useful job as part of a small cleaning crew than he is today sitting idle and unproductive in an institution.
The danger is a caste system. A Western tourist in India in the early 1900's reported that after a cat had kittens under her bed, there was a long discussion between the hotel employees about which caste and employment category's job it should be to remove them. In the bad old days of unionization in the US, a union electrician wouldn't mount an electrical box: a union carpenter had to be called and paid for a day's work. If specialists can easily be summoned to do each particular job, it may encourage employees to become choosy and inflexible about the work they will and will not do, and employers to further de-skill the majority of jobs because someone with special skills can do the parts requiring training and expertise.
The result could be a replay of Detroit-vs-Japan in the 1970's and 1980's. The giant American carmakers firmly believed that the future was "workerless factories", and their workers and unions knew it and dug in their heels to fight innovations. Meanwhile, the Japanese carmakers had long ago made peace with the post-WWII laws (shoved down their throats by General MacArthur's pinko advisors, mostly) that made workers almost un-fireable. As a result, they had a relatively cooperative relationship with their unions and a paternalistic one with employees. Also, as new entrants in the automobile business, workers and management both knew they needed to cooperate to build their company and improve their common future.
In this environment, it was much easier to introduce radical changes. Automation wasn't feared -- workers gave robots names and appreciated their doing dangerous and boring jobs. Statistical quality control, quality circles, and the like made continuous incremental improvements in the existing process instead of big bitterly-contested revolutions being imposed from the top.
Therefore, employers who pigeon-hole people entirely and employees who take a "not my job" attitude will tend to be associated with poor results. (If people are so inflexible that their employer doesn't need them to learn new skills, their work is probably so routine that it should be mechanized or out-sourced to where labor is cheaper.) Learning theory says we have a "zone of proximal development" where learning is fastest. Outside that, they should bring in an expert to do the job, perhaps asking them to teach an employee as they do.